/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.eclipse.gemini.blueprint.test.legacyspringsupport;


import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.LinkedList;
import java.util.List;

import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.util.Assert;

/**
 * <p>
 * Convenient superclass for JUnit 3.8 based tests depending on a Spring
 * context. The test instance itself is populated by Dependency Injection.
 * </p>
 * <p>
 * Really for integration testing, not unit testing. You should <i>not</i>
 * normally use the Spring container for unit tests: simply populate your POJOs
 * in plain JUnit tests!
 * </p>
 * <p>
 * This supports two modes of populating the test:
 * </p>
 * <ul>
 * <li>Via Setter Dependency Injection. Simply express dependencies on objects
 * in the test fixture, and they will be satisfied by autowiring by type.
 * <li>Via Field Injection. Declare protected variables of the required type
 * which match named beans in the context. This is autowire by name, rather than
 * type. This approach is based on an approach originated by Ara Abrahmian.
 * Setter Dependency Injection is the default: set the
 * {@code populateProtectedVariables} property to {@code true} in
 * the constructor to switch on Field Injection.
 * </ul>
 *
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Rick Evans
 * @author Sam Brannen
 * @since 1.1.1
 * @see #setDirty
 * @see #contextKey
 * @see #getContext
 * @see #getConfigLocations
 * @deprecated as of Spring 3.0, in favor of using the listener-based test context framework
 * ({@link org.springframework.test.context.junit4.AbstractJUnit4SpringContextTests})
 */
@Deprecated
@SuppressWarnings({ "unchecked", "rawtypes" })
public abstract class AbstractDependencyInjectionSpringContextTests extends AbstractSingleSpringContextTests {

    /**
     * Constant that indicates no autowiring at all.
     *
     * @see #setAutowireMode
     */
    public static final int AUTOWIRE_NO = 0;

    /**
     * Constant that indicates autowiring bean properties by name.
     *
     * @see #setAutowireMode
     */
    public static final int AUTOWIRE_BY_NAME = AutowireCapableBeanFactory.AUTOWIRE_BY_NAME;

    /**
     * Constant that indicates autowiring bean properties by type.
     *
     * @see #setAutowireMode
     */
    public static final int AUTOWIRE_BY_TYPE = AutowireCapableBeanFactory.AUTOWIRE_BY_TYPE;

    private boolean populateProtectedVariables = false;

    private int autowireMode = AUTOWIRE_BY_TYPE;

    private boolean dependencyCheck = true;

    private String[] managedVariableNames;


    /**
     * Default constructor for AbstractDependencyInjectionSpringContextTests.
     */
    public AbstractDependencyInjectionSpringContextTests() {
    }

    /**
     * Constructor for AbstractDependencyInjectionSpringContextTests with a
     * JUnit name.
     * @param name the name of this text fixture
     */
    public AbstractDependencyInjectionSpringContextTests(String name) {
        super(name);
    }


    /**
     * Set whether to populate protected variables of this test case. Default is
     * {@code false}.
     */
    public final void setPopulateProtectedVariables(boolean populateFields) {
        this.populateProtectedVariables = populateFields;
    }

    /**
     * Return whether to populate protected variables of this test case.
     */
    public final boolean isPopulateProtectedVariables() {
        return this.populateProtectedVariables;
    }

    /**
     * Set the autowire mode for test properties set by Dependency Injection.
     * <p>The default is {@link #AUTOWIRE_BY_TYPE}. Can be set to
     * {@link #AUTOWIRE_BY_NAME} or {@link #AUTOWIRE_NO} instead.
     * @see #AUTOWIRE_BY_TYPE
     * @see #AUTOWIRE_BY_NAME
     * @see #AUTOWIRE_NO
     */
    public final void setAutowireMode(final int autowireMode) {
        this.autowireMode = autowireMode;
    }

    /**
     * Return the autowire mode for test properties set by Dependency Injection.
     */
    public final int getAutowireMode() {
        return this.autowireMode;
    }

    /**
     * Set whether or not dependency checking should be performed for test
     * properties set by Dependency Injection.
     * <p>The default is {@code true}, meaning that tests cannot be run
     * unless all properties are populated.
     */
    public final void setDependencyCheck(final boolean dependencyCheck) {
        this.dependencyCheck = dependencyCheck;
    }

    /**
     * Return whether or not dependency checking should be performed for test
     * properties set by Dependency Injection.
     */
    public final boolean isDependencyCheck() {
        return this.dependencyCheck;
    }

    /**
     * Prepare this test instance, injecting dependencies into its protected
     * fields and its bean properties.
     * <p>Note: if the {@link ApplicationContext} for this test instance has not
     * been configured (e.g., is {@code null}), dependency injection
     * will naturally <strong>not</strong> be performed, but an informational
     * message will be written to the log.
     * @see #injectDependencies()
     */
    protected void prepareTestInstance() throws Exception {
        if (getApplicationContext() == null) {
            if (this.logger.isInfoEnabled()) {
                this.logger.info("ApplicationContext has not been configured for test [" + getClass().getName()
                        + "]: dependency injection will NOT be performed.");
            }
        }
        else {
            injectDependencies();
        }
    }

    /**
     * Inject dependencies into 'this' instance (that is, this test instance).
     * <p>The default implementation populates protected variables if the
     * {@link #populateProtectedVariables() appropriate flag is set}, else uses
     * autowiring if autowiring is switched on (which it is by default).
     * <p>Override this method if you need full control over how dependencies are
     * injected into the test instance.
     * @throws Exception in case of dependency injection failure
     * @throws IllegalStateException if the {@link ApplicationContext} for this
     * test instance has not been configured
     * @see #populateProtectedVariables()
     */
    @SuppressWarnings("javadoc")
    protected void injectDependencies() throws Exception {
        Assert.state(getApplicationContext() != null,
                "injectDependencies() called without first configuring an ApplicationContext");
        if (isPopulateProtectedVariables()) {
            if (this.managedVariableNames == null) {
                initManagedVariableNames();
            }
            populateProtectedVariables();
        }
        getApplicationContext().getBeanFactory().autowireBeanProperties(this, getAutowireMode(), isDependencyCheck());
    }

    private void initManagedVariableNames() throws IllegalAccessException {
        List managedVarNames = new LinkedList();
        Class clazz = getClass();
        do {
            Field[] fields = clazz.getDeclaredFields();
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Found " + fields.length + " fields on " + clazz);
            }
            for (int i = 0; i < fields.length; i++) {
                Field field = fields[i];
                field.setAccessible(true);
                if (this.logger.isDebugEnabled()) {
                    this.logger.debug("Candidate field: " + field);
                }
                if (isProtectedInstanceField(field)) {
                    Object oldValue = field.get(this);
                    if (oldValue == null) {
                        managedVarNames.add(field.getName());
                        if (this.logger.isDebugEnabled()) {
                            this.logger.debug("Added managed variable '" + field.getName() + "'");
                        }
                    }
                    else {
                        if (this.logger.isDebugEnabled()) {
                            this.logger.debug("Rejected managed variable '" + field.getName() + "'");
                        }
                    }
                }
            }
            clazz = clazz.getSuperclass();
        } while (!clazz.equals(AbstractDependencyInjectionSpringContextTests.class));

        this.managedVariableNames = (String[]) managedVarNames.toArray(new String[managedVarNames.size()]);
    }

    private boolean isProtectedInstanceField(Field field) {
        int modifiers = field.getModifiers();
        return !Modifier.isStatic(modifiers) && Modifier.isProtected(modifiers);
    }

    private void populateProtectedVariables() throws IllegalAccessException {
        for (int i = 0; i < this.managedVariableNames.length; i++) {
            String varName = this.managedVariableNames[i];
            Object bean = null;
            try {
                Field field = findField(getClass(), varName);
                bean = getApplicationContext().getBean(varName, field.getType());
                field.setAccessible(true);
                field.set(this, bean);
                if (this.logger.isDebugEnabled()) {
                    this.logger.debug("Populated field: " + field);
                }
            }
            catch (NoSuchFieldException ex) {
                if (this.logger.isWarnEnabled()) {
                    this.logger.warn("No field with name '" + varName + "'");
                }
            }
            catch (NoSuchBeanDefinitionException ex) {
                if (this.logger.isWarnEnabled()) {
                    this.logger.warn("No bean with name '" + varName + "'");
                }
            }
        }
    }

    private Field findField(Class clazz, String name) throws NoSuchFieldException {
        try {
            return clazz.getDeclaredField(name);
        }
        catch (NoSuchFieldException ex) {
            Class superclass = clazz.getSuperclass();
            if (superclass != AbstractSpringContextTests.class) {
                return findField(superclass, name);
            }
            else {
                throw ex;
            }
        }
    }

}